Yeah, dismissing Geno's popularity is also dismissing a key merit of Banjo's. And I believe each would rely on fan demand to overcome bigger names from their respective companies. However, I believe Banjo has additional merits past his popularity that Geno lacks, which would be decisive in his inclusion. Not to say the popularity wouldn't do the heavy lifting, or prompt initial consideration, I just don't believe that Banjo's inclusion would be 100% owing to active fan pull, where I do believe Geno's would be. Putting moveset potential aside of course, as basically all candidates have it.That is true but it doesn't matter all that much. I'm not comparing which of the two deserves to be in Smash more. I'm talking about how they are in an extremely similar position which is they are relying 100% on fan pull to be given a place on the roster despite the abundance of much bigger names of the host company. And that Banjo fans giving examples of why a character like Geno's popularity shouldn't matter isn't good for us.
I mean, maybe fan pull is what brings them under review in the first place (and thus is obviously crucial), but as one has virtually no presence and little recognition outside the Smash diehard fanbase, and the other does, factors further than popularity prove influential as well. Even if they're not the dominant driving force, they're probably the clincher.
So while I would ascribe Geno's inclusion to 100% diehard fan demand (which is a tough sell for standalone content given characters with wider appeal) I'd say the rationale behind Banjo's inclusion, though predominantly fan-driven, is more multifaceted.